Immune reconstitution inflammatory syndrome associated with disseminated mycobacterial infection in patients with AIDS

Management of the immune reconstitution inflammatory syndrome

The immune reconstitution inflammatory syndrome (IRIS) is a frequent early complication of antiretroviral therapy (ART) in patients with advanced HIV. Because there is no confirmatory diagnostic test, the diagnosis is based on clinical presentation and exclusion of alternative causes for deterioration, such as antimicrobial drug resistance. Opportunistic infection treatment should be optimized. Mild cases may require symptomatic therapy alone or nonsteroidal anti-inflammatory drugs. Corticosteroids have been used to treat more severe cases of IRIS associated with mycobacterial and fungal infections. There is evidence from a randomized controlled trial that prednisone reduces morbidity and improves symptoms in paradoxical tuberculosis (TB)-IRIS. Neurological TB-IRIS is potentially life-threatening; high-dose corticosteroids are indicated and ART interruption should be considered if level of consciousness is depressed. When considering corticosteroid treatment clinicians should be aware of their side effects and only use them when the diagnosis of IRIS is certain. In viral forms of IRIS corticosteroids are generally avoided.

Frequency, severity, and prediction of tuberculous meningitis immune reconstitution inflammatory syndrome

BACKGROUND

Tuberculosis immune reconstitution inflammatory syndrome (IRIS) is a common cause of deterioration in human immunodeficiency virus (HIV)-infected patients receiving tuberculosis treatment after starting antiretroviral therapy (ART). Potentially life-threatening neurological involvement occurs frequently and has been suggested as a reason to defer ART.

METHODS

We conducted a prospective study of HIV-infected, ART-naive patients with tuberculous meningitis (TBM). At presentation, patients started tuberculosis treatment and prednisone; ART was initiated 2 weeks later. Clinical and laboratory findings were compared between patients who developed TBM-IRIS (TBM-IRIS patients) and those who did not (non-TBM-IRIS patients). A logistic regression model was developed to predict TBM-IRIS.

RESULTS

Forty-seven percent (16/34) of TBM patients developed TBM-IRIS, which manifested with severe features of inflammation. At TBM diagnosis, TBM-IRIS patients had higher cerebrospinal fluid (CSF) neutrophil counts compared with non-TBM-IRIS patients (median, 50 vs 3 cells ×10(6)/L, P = .02). Mycobacterium tuberculosis was cultured from CSF of 15 TBM-IRIS patients (94%) compared with 6 non-TBM-IRIS patients (33%) at time of TBM diagnosis; relative risk of developing TBM-IRIS if CSF was Mycobacterium tuberculosis culture positive = 9.3 (95% confidence interval [CI], 1.4-62.2). The combination of high CSF tumor necrosis factor (TNF)-α and low interferon (IFN)-γ at TBM diagnosis predicted TBM-IRIS (area under the curve = 0.91 [95% CI, .53-.99]).

CONCLUSIONS

TBM-IRIS is a frequent, severe complication of ART in HIV-associated TBM and is characterized by high CSF neutrophil counts and Mycobacterium tuberculosis culture positivity at TBM presentation. The combination of CSF IFN-γ and TNF-α concentrations may predict TBM-IRIS and thereby be a means to individualize patients to early or deferred ART.

Modulation of innate host factors by Mycobacterium avium complex in human macrophages includes interleukin 17

BACKGROUND

Although opportunistic infections due to Mycobacterium avium complex (MAC) have been less common since the introduction of highly active antiretroviral therapy, globally, human immunodeficiency virus-1 (HIV-1)-positive patients remain predisposed to these infections. Absence of a properly functioning acquired immune response allows MAC persistence within macrophages localized in lymph nodes coinfected with HIV and MAC. Although a deficiency in interferon γ appears to play a part in the ability of MAC to deflect the macrophage-associated antimicrobial attack, questions about this process remain. Our study examines the ability of MAC to regulate interleukin 17 (IL-17), a proinflammatory cytokine involved in host cell recruitment.

METHODS

Coinfected lymph nodes were examined for IL-17 by immunohistochemical analysis. In vitro, macrophages exposed to mycobacteria were evaluated for transcription activities, proteins, and signaling pathways responsible for IL-17 expression. Infected macrophages were also analyzed for expression of interleukin 21 (IL-21) and negative regulators of immune responses.

RESULTS

Infection of macrophages triggered synthesis of IL-17, correlating with IL-17 expression by macrophages in coinfected lymph nodes. Infected macrophages exposed to exogenous IL-17 expressed CXCL10, which favors recruitment of new macrophages as targets for infection. Blockade of nuclear factor κ-light-chain-enhancer of activated B cells and mitogen-activated protein kinase pathways suppressed mycobacteria-induced IL-17 expression. MAC triggered expression of IL-21, IRF4, and STAT3 genes related to IL-17 regulation, as well as expression of the negative immunoregulators CD274(PD-L1) and suppressors of cytokine signaling.

CONCLUSIONS

MAC-infected macrophages can provide an alternative source for IL-17 that favors accumulation of new targets for perpetuating bacterial and viral infection while suppressing host antimicrobial immune responses.

Central nervous system immune reconstitution inflammatory syndrome in AIDS: experience of a Mexican neurological centre

BACKGROUND

Highly active antiretroviral therapy (HAART) restores the inflammatory immune response in AIDS patients and it may unmask previous subclinical infections or paradoxically exacerbate symptoms of opportunistic infections. Up to 25% of patients receiving HAART develop immune reconstitution inflammatory syndrome (IRIS). We describe six patients with IRIS central nervous system (CNSIRIS) manifestations emphasizing the relevance of CSF cultures and neuroimaging in early diagnosis and management.

METHODS

Patients with CNSIRIS were identified among hospitalized HIV-infected patients that started HAART from January 2002 through December 2007 at a referral neurological center in Mexico.

RESULTS

One-hundred and forty-two HIV-infected patients with neurological signs were hospitalized, 64 of which had received HAART, and six (9.3%) developed CNSIRIS. Five patients were male. Two cases of tuberculosis, two of cryptococcosis, one of brain toxoplasmosis, and one possible PML case were found. IRIS onset occurred within 12 weeks of HAART in five patients. Anti-infective therapy was continued. In one case, HAART was temporarily suspended. In long-term follow-up the clinical condition improved in all patients.

CONCLUSIONS

CNSIRIS associated to opportunistic infections appeared in 9% of patients receiving HAART. Interestingly, no cases of malignancy or neoplasm IRIS-related were found. Frequent clinical assessment and neuroimaging studies supported diagnosis and treatment. Risk factors were similar to those found in other series.

HIV-associated tuberculous meningitis--diagnostic and therapeutic challenges

HIV-associated tuberculous meningitis (TBM) poses significant diagnostic and therapeutic challenges and carries a dismal prognosis. In this review, we present the clinical features and management of HIV-associated TBM, and compare this to disease in HIV-uninfected individuals. Although the clinical presentation, laboratory findings and radiological features of TBM are similar in HIV-infected and HIV-uninfected patients, some important differences exist. HIV-infected patients present more frequently with extra-meningeal tuberculosis and systemic features of HIV infection. In HIV-associated TBM, clinical course and outcome are influenced by profound immunosuppression at presentation, emphasising the need for earlier diagnosis of HIV infection and initiation of antiretroviral treatment.

Management of patients with the immune reconstitution inflammatory syndrome

A significant proportion of patients present with the immune reconstitution inflammatory syndrome (IRIS) after commencing antiretroviral therapy (ART). This syndrome is most frequently associated with infective causes. The lack of evidence-based treatment guidelines poses challenges in the management of these patients. Alternative causes for deterioration should be excluded, and optimization of treatment for the underlying opportunistic infection is essential. In addition, anti-inflammatory or immunomodulatory therapy may be considered, particularly in severe cases. Corticosteroids, the only treatment for which clinical trial data exist (for treating paradoxical tuberculosis-associated IRIS), are the treatment most frequently used in IRIS. Limited anecdotal reports of benefit exist for other agents, including NSAIDs, pentoxifylline, montelukast, thalidomide, and hydroxychloroquine. Therapeutic procedures (eg, aspiration of pus collections) play an important role in some patients. Interruption of ART may be considered in life-threatening forms of IRIS.

Chronic colitis associated with HIV infection can be related to intraepithelial infiltration of the colon by CD8+ T lymphocytes

Gastrointestinal complications in AIDS patients with diarrhoea are common clinical manifestations, frequently diagnosed by colonoscopy as non-specific colitis. We retrospectively study colon biopsies diagnosed as chronic colitis associated with HIV (CCH). Biopsies were sorted as patients with AIDS (serum CD4 <200 cell/mm3) but without any clear infectious process (n = 12) and patients without HIV infection (n = 24). There are low numbers of CD4+ T lymphocytes in lamina propria of AIDS patients, but CD8+ T populations in this area appear to be similar in all studied groups, regardless of HIV infection or laboratory evidence of a specific agent. We found the clear evidence of CD8+ T cells infiltration in colonic mucosa in HIV patients with microscopic colitis. An imbalance of lymphocyte subpopulations in the colon, both in the lamina propria and epithelium, could result in an intraepithelial CD8 infiltration, involved in the pathogenesis of CCH in AIDS patients.

The effects of human herpesvirus 8 infection and interferon-gamma response in cutaneous lesions of Kaposi sarcoma differ among human immunodeficiency virus-infected and uninfected individuals

BACKGROUND

Kaposi sarcoma (KS) is associated with human herpesvirus 8 (HHV-8). The cutaneous immune response in this tumour is not well established and a better understanding is necessary.

OBJECTIVES

To evaluate the HHV-8 expression and immune response in cutaneous lesions of classic KS (CKS) and AIDS-associated KS (AIDS-KS).

METHODS

We performed a quantitative immunohistochemical study of cells expressing HHV-8 latency-associated nuclear antigen (LANA), CD4, CD8 and interferon (IFN)-gamma in skin lesions from patients with CKS and AIDS-KS (with or without highly active antiretroviral therapy, HAART).

RESULTS

CKS showed higher LANA expression compared with AIDS-KS, regardless of HAART. We also found higher LANA expression in nodules compared with patch/plaque lesions. The tissue CD4+ cell proportion was lower in AIDS-KS patients without HAART than in patients with CKS. In CKS lesions, CD4+ and CD8+ cells expressed IFN-gamma, as shown by double immunostaining. AIDS-KS presented low numbers of IFN-gamma-expressing cells. CD8+ cell numbers were similar in all groups, which appeared unrelated to the clinical or epidemiological type of KS.

CONCLUSIONS

Our quantitative data on the pattern of KS lesions in selected groups of patients, as shown by in situ immune response, demonstrated a CD4+ T-cell involvement associated with IFN-gamma, an environment of immune response-modified human immunodeficiency virus (HIV) infection. In our sample, the promotion of KS in patients without HIV appears to be related to higher HHV-8 load or virulence than in those with AIDS. This higher resistance may be explained by a sustained immune response against this herpesvirus, that is only partially restored but effective after HAART.